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  Subjects -> AERONAUTICS AND SPACE FLIGHT (Total: 120 journals)
Showing 1 - 30 of 30 Journals sorted alphabetically
Acta Astronautica     Hybrid Journal   (Followers: 483)
Advances in Aerospace Engineering     Open Access   (Followers: 66)
Advances in Aerospace Science and Technology     Open Access   (Followers: 7)
Advances in Astronautics Science and Technology     Hybrid Journal  
Advances in Space Research     Full-text available via subscription   (Followers: 454)
Aeronautical Journal, The     Hybrid Journal   (Followers: 10)
Aerospace     Open Access   (Followers: 57)
Aerospace Medicine and Human Performance     Full-text available via subscription   (Followers: 14)
Aerospace Science and Technology     Hybrid Journal   (Followers: 422)
Aerospace Scientific Journal     Open Access   (Followers: 15)
Aerospace Systems     Hybrid Journal   (Followers: 3)
Aerospace technic and technology     Open Access   (Followers: 2)
Aerotecnica Missili & Spazio : Journal of Aerospace Science, Technologies & Systems     Hybrid Journal  
AIAA Journal     Hybrid Journal   (Followers: 1175)
Air Force Magazine     Full-text available via subscription   (Followers: 11)
Air Medical Journal     Hybrid Journal   (Followers: 8)
Annual of Navigation     Open Access   (Followers: 22)
Artificial Satellites     Open Access   (Followers: 23)
ASTRA Proceedings     Open Access   (Followers: 2)
Astrodynamics     Hybrid Journal   (Followers: 1)
Aviation     Open Access   (Followers: 15)
Aviation Advances & Maintenance     Open Access   (Followers: 3)
Aviation in Focus - Journal of Aeronautical Sciences     Open Access   (Followers: 10)
Aviation Psychology and Applied Human Factors     Hybrid Journal   (Followers: 26)
Aviation Week     Full-text available via subscription   (Followers: 438)
Canadian Aeronautics and Space Journal     Full-text available via subscription   (Followers: 33)
CEAS Aeronautical Journal     Hybrid Journal   (Followers: 29)
Chinese Journal of Aeronautics     Open Access   (Followers: 20)
Ciencia y Poder Aéreo     Open Access   (Followers: 2)
Civil Aviation High Technologies     Open Access   (Followers: 5)
Control Systems     Hybrid Journal   (Followers: 317)
Cosmic Research     Hybrid Journal   (Followers: 4)
COSPAR Colloquia Series     Full-text available via subscription   (Followers: 11)
Egyptian Journal of Remote Sensing and Space Science     Open Access   (Followers: 24)
Elsevier Astrodynamics Series     Full-text available via subscription   (Followers: 12)
Fatigue of Aircraft Structures     Open Access   (Followers: 15)
Frontiers in Astronomy and Space Sciences     Open Access   (Followers: 12)
Gyroscopy and Navigation     Hybrid Journal   (Followers: 255)
IEEE Aerospace and Electronic Systems Magazine     Full-text available via subscription   (Followers: 276)
IEEE Journal on Miniaturization for Air and Space Systems     Hybrid Journal   (Followers: 2)
IEEE Transactions on Aerospace and Electronic Systems     Hybrid Journal   (Followers: 383)
IEEE Transactions on Circuits and Systems I: Regular Papers     Hybrid Journal   (Followers: 39)
International Journal of Aeroacoustics     Hybrid Journal   (Followers: 39)
International Journal of Aerodynamics     Hybrid Journal   (Followers: 36)
International Journal of Aeronautical and Space Sciences     Hybrid Journal   (Followers: 2)
International Journal of Aerospace Engineering     Open Access   (Followers: 80)
International Journal of Aerospace Psychology     Hybrid Journal   (Followers: 23)
International Journal of Aerospace Sciences     Open Access   (Followers: 30)
International Journal of Applied Geospatial Research     Hybrid Journal   (Followers: 7)
International Journal of Aviation Management     Hybrid Journal   (Followers: 8)
International Journal of Aviation Technology, Engineering and Management     Full-text available via subscription   (Followers: 7)
International Journal of Aviation, Aeronautics, and Aerospace     Open Access   (Followers: 4)
International Journal of Crashworthiness     Hybrid Journal   (Followers: 12)
International Journal of Micro Air Vehicles     Full-text available via subscription   (Followers: 11)
International Journal of Satellite Communications Policy and Management     Hybrid Journal   (Followers: 13)
International Journal of Space Science and Engineering     Hybrid Journal   (Followers: 11)
International Journal of Space Structures     Full-text available via subscription   (Followers: 17)
International Journal of Space Technology Management and Innovation     Full-text available via subscription   (Followers: 10)
International Journal of Sustainable Aviation     Hybrid Journal   (Followers: 5)
International Journal of Turbo and Jet-Engines     Hybrid Journal   (Followers: 6)
Investigación Pecuaria     Open Access   (Followers: 3)
Journal of Aerodynamics     Open Access   (Followers: 17)
Journal of Aeronautical Materials     Open Access   (Followers: 9)
Journal of Aeronautics & Aerospace Engineering     Open Access   (Followers: 28)
Journal of Aerospace Engineering     Full-text available via subscription   (Followers: 68)
Journal of Aerospace Engineering & Technology     Full-text available via subscription   (Followers: 16)
Journal of Aerospace Information Systems     Hybrid Journal   (Followers: 20)
Journal of Aerospace Information Systems     Hybrid Journal   (Followers: 32)
Journal of Aerospace Technology and Management     Open Access   (Followers: 7)
Journal of Aircraft     Hybrid Journal   (Followers: 337)
Journal of Aircraft and Spacecraft Technology     Open Access   (Followers: 8)
Journal of Airline and Airport Management     Open Access   (Followers: 12)
Journal of Astrobiology & Outreach     Open Access   (Followers: 3)
Journal of Aviation Technology and Engineering     Open Access   (Followers: 11)
Journal of Aviation/Aerospace Education & Research     Open Access   (Followers: 2)
Journal of Engineering and Technological Sciences     Open Access   (Followers: 1)
Journal of Guidance, Control, and Dynamics     Hybrid Journal   (Followers: 204)
Journal of KONBiN     Open Access   (Followers: 3)
Journal of Navigation     Hybrid Journal   (Followers: 279)
Journal of Propulsion and Power     Hybrid Journal   (Followers: 610)
Journal of Space Safety Engineering     Hybrid Journal   (Followers: 7)
Journal of Space Weather and Space Climate     Open Access   (Followers: 27)
Journal of Spacecraft and Rockets     Hybrid Journal   (Followers: 770)
Journal of Spatial Science     Hybrid Journal   (Followers: 3)
Journal of the American Helicopter Society     Full-text available via subscription   (Followers: 7)
Journal of the Astronautical Sciences     Hybrid Journal   (Followers: 8)
Journal of the Australasian Society of Aerospace Medicine     Open Access   (Followers: 1)
Journal of Wind Engineering and Industrial Aerodynamics     Hybrid Journal   (Followers: 16)
Life Sciences in Space Research     Hybrid Journal   (Followers: 3)
MAD - Magazine of Aviation Development     Open Access   (Followers: 2)
Mekanika : Jurnal Teknik Mesin i     Open Access   (Followers: 1)
Microgravity Science and Technology     Hybrid Journal   (Followers: 2)
New Space     Hybrid Journal   (Followers: 6)
Nonlinear Dynamics     Hybrid Journal   (Followers: 19)
npj Microgravity     Open Access   (Followers: 3)
Open Aerospace Engineering Journal     Open Access   (Followers: 1)
Population Space and Place     Hybrid Journal   (Followers: 9)
Problemy Mechatroniki. Uzbrojenie, lotnictwo, inżynieria bezpieczeństwa / Problems of Mechatronics. Armament, Aviation, Safety Engineering     Open Access   (Followers: 3)
Proceedings of the Human Factors and Ergonomics Society Annual Meeting     Hybrid Journal   (Followers: 16)
Proceedings of the Institution of Mechanical Engineers Part G: Journal of Aerospace Engineering     Hybrid Journal   (Followers: 45)
Progress in Aerospace Sciences     Full-text available via subscription   (Followers: 79)
Propulsion and Power Research     Open Access   (Followers: 67)
REACH - Reviews in Human Space Exploration     Full-text available via subscription   (Followers: 5)
Research & Reviews : Journal of Space Science & Technology     Full-text available via subscription   (Followers: 17)
RocketSTEM     Free   (Followers: 6)
Russian Aeronautics (Iz VUZ)     Hybrid Journal   (Followers: 24)
Science and Education : Scientific Publication of BMSTU     Open Access   (Followers: 1)
Space and Polity     Hybrid Journal   (Followers: 4)
Space Policy     Hybrid Journal   (Followers: 30)
Space Research Today     Full-text available via subscription   (Followers: 48)
Space Safety Magazine     Free   (Followers: 51)
Space Science International     Open Access   (Followers: 192)
Space Science Reviews     Hybrid Journal   (Followers: 97)
SpaceNews     Free   (Followers: 824)
Spatial Information Research     Hybrid Journal   (Followers: 1)
Technical Soaring     Full-text available via subscription   (Followers: 1)
Transport and Aerospace Engineering     Open Access   (Followers: 1)
Transportmetrica A : Transport Science     Hybrid Journal   (Followers: 8)
Unmanned Systems     Hybrid Journal   (Followers: 5)
Вісник Національного Авіаційного Університету     Open Access   (Followers: 2)

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Journal Cover
Aerospace Systems
Number of Followers: 3  
  Hybrid Journal Hybrid journal (It can contain Open Access articles)
ISSN (Print) 2523-3947 - ISSN (Online) 2523-3955
Published by Springer-Verlag Homepage  [2626 journals]
  • Effect of tip injection on the flow characteristics of an aeroengine
           compressor rotor
    • Abstract: Existing experiments, simulations, and analysis have shown that the flow field of the blade tip has a significant effect on rotating stall and acoustic resonance in aeroengine compressors. Based on the numerical simulation of NASA rotor 37, the steady influence of air injection at blade tip was investigated in this investigation. The results show that the injected flow could obviously extend the stability margin of the axial compressor to varying degrees. The tip injection reduces the blockage caused by the tip leakage, and reduces the backflow in the trailing edge area of the blade tip, thereby delaying the occurrence of stall. Furthermore, in this paper, different types of rotors are constructed to verify the effect of injection parameters on the stability extension. The results show that the improvement of rotor stall margin is positively correlated with the injector inlet total pressure, and when the injector inlet flow conditions are of the same magnitude, the improvement of the rotor stall margin is negatively related to the distance between the injector and the leading edge of the blade.
      PubDate: 2021-01-14
  • Adaptive filter based on Monte Carlo method to improve the non-linear
           target tracking in the radar system
    • Abstract: This article deals with the problem of degraded tracking performance of a high non-linear target in a radar system, well known by the divergence phenomenon. In our study, we aim to improve the target state estimation to imitate the tracking scenario as well as avoid the last cited undesirable phenomenon, generated during the non-linear measurements filtering, once using extended KALMAN filter. To overcome this issue, we have implemented a new approach based on the adaptive Monte Carlo (AMC) algorithm to replace the traditional method as is known by the extended KALMAN filter (EKF). The obtained experimental results showed a challenging remediation. Where, the AMC converges towards the accurate state estimation. Thus, more efficient than extended KALMAN filter. The experimental results prove that the designed system meets the objectives set for AMC referring to an experimental database obtained by a radar system, using MATLAB software development framework.
      PubDate: 2021-01-14
  • Aerial image detection and recognition system based on deep neural network
    • Abstract: Aerial image detection aims to find objects of interest and give their locations, and the goal of aerial image recognition is to classify the scenes or objects. Deep neural network is by far the best model for image detection and recognition. But still it fails to meet the requirements of high precision and low missing alarm. To solve this issue, we propose a two-step system including detection and fine-grained recognition modules. The first module is based on one-stage detection method YOLOv3. Furthermore, the metric-learning-based magnet loss is introduced to realize fine-grain recognition in the second step. The experiments prove the effectiveness of their combinations on improving precision and reducing missing alarm rate.
      PubDate: 2021-01-03
  • Analysis of BDS GEO satellite multipath effect for GNSS integrity
           monitoring in civil aviation
    • Abstract: With the great development of Global Navigation Satellite System (GNSS), multi-GNSS constellations (GPS, BDS, GLONASS, and Galileo) are able to provide users with more accurate positioning result. For civil aviation, to guarantee user’s safety, multi-constellation GNSS needs to meet the integrity requirement. Using conservative error models, Multiple Hypothesis Solution Separation (MHSS) Advanced Receiver Autonomous Integrity Monitoring (ARAIM) is proposed to evaluate GNSS integrity. Current multipath error model in ARAIM algorithm is based on data of GPS Medium Earth Orbit (MEO) satellites. But BDS is a hybrid constellation. For BDS II, there has 5 Geosynchronous Earth Orbit (GEO) satellites. Previous studies have shown that the multipath effect of GEO satellites has statistical characteristics different from MEO satellites. Meanwhile, the multipath magnitude of GEO satellites is larger than that of MEO satellites. This paper mainly focuses on validating whether the multipath error model in ARAIM algorithm is conservative enough for GEO satellites. In this paper, Code Minus Carrier (CMC) residuals are calculated for BDS GEO dual-frequency signals. Then the Standard Deviation (STD) of CMC residuals can be conservatively estimated by bounded Cumulative Distribution Function (CDF). After eliminating interference from receiver noise, STD of GEO multipath can be obtained. Comparing the STD of GEO multipath effect with ARAIM multipath error model, a conclusion could be drawn that current multipath error model in ARAIM algorithm is no longer able to conservatively estimate the statistical characteristics of GEO satellites.
      PubDate: 2021-01-02
  • Behavior of mixing enhancement in microscale shock cylindrical bubble
    • Abstract: The investigation in the mixing characteristics of microscale shock cylindrical bubble interaction (SBI) provides a fundamental perspective into the microscale fuel injection. In present paper, the mixing performance of multi-scale SBI is numerically studied based on compressible Navier–Stokes equation. Starting from the bubble morphology, a scaling behavior of concentration distribution is exhibited in macroscale dynamics, whereas a superior capability of concentration decaying is observed in microscale cases. On the basis of mixedness evaluation, the mixing property of microscale bubbles is reinforced in the pre-interaction stage with notable viscous diffusion, and suppressed in the later evolution in the absence of vortex formation. Resorting to the Lagrangian coherent structure, a spatial coincidence between fluid stretching and mixing extent is visualized. The present study attempts to clarify the physical rationality of microscale injection strategies such as the atomization process and multiple micro-nozzles for mixing enhancement. Further efforts are devoted to physically modelling the competing mechanism of stirring effect (macroscale dynamics) and viscous diffusion (microscale dynamics) for optimal mixing performance.
      PubDate: 2021-01-02
  • Analysis and experimental study on different airfoils in heavy unmanned
           aerial vehicle
    • Abstract: The performance of airfoil plays an important role in the performance of model aircraft. Three types of airfoils are selected in this paper: the GOE 480, MH 114, and MH 115, which are all flat-convex airfoils. Firstly, three types of airfoil were numerically analyzed by using Profili software. The results show that among the three types of flat-convex airfoils, the lift-drag ratio of MH series airfoils is higher than that of GOE 480. Then, the FEA software was used to analyze the aerodynamic performance of the wings. And the lift and drag coefficient obtained from calculation was compared with the results by Profili software. To compare the actual flight performance of the three airfoils, the control variable method and UAV self speed measurement method based on sequence images were used for the real field test. The results show that the type of MH 115 has the largest max level speed among the three types of wings.
      PubDate: 2020-11-20
  • State-based safety analysis method for dynamic evaluation of failure
    • Abstract: System state that represents a combined influence of internal and external system parameters on the overall failure effect plays a significant role in failure effect analysis. The traditional safety analysis methods can hardly evaluate the overall failure impact due to the dynamic failure behaviors in diverse system interaction situations. To overcome this problem, this paper proposes a state-based safety analysis method for dynamic evaluation of the failure effect combining the situation factor. First, a hierarchical modeling framework that includes functional logic, physical architecture, and the failure mode is constructed, and then the cross-linking relationships between items are characterized by the state machines. Particularly, the event transmission mechanism and the global attribute updating mechanism are designed to realize the state synchronization of various systems, thus enabling the global propagation of failure. The feasibility of the proposed method is verified by simulations. The Enterprise Architect platform is used to model the aircraft integrated surveillance system and analyze the effects of different failure modes in typical situations. The proposed method complements the failure effect evaluation accuracy considering the dynamic interaction situations, thus realizing the global perception of the safety state, enhancing the dynamics and integrity of the failure effect analysis process.
      PubDate: 2020-11-19
  • Spatio-temporal graph convolutional neural network for remaining useful
           life estimation of aircraft engines
    • Abstract: Accurate remaining useful life (RUL) estimation is crucial for the maintenance of complex systems, e.g. aircraft engines. Thanks to the popularity of sensors, data-driven methods are widely used to evaluate RULs of systems especially deep learning approaches. Though remarkably capable at non-linear modeling, deep learning-based prognostics techniques lack powerful spatio-temporal learning ability. For instance, convolutional neural networks are restricted to only process grid structures rather than general domains, recurrent neural networks neglect spatial relations between sensors and suffer from long-term dependency learning. To solve these problems, we construct a graph structure on sensor network with Pearson Correlation Coefficients among sensors and propose a method for combining the power of graph convolutional network on spatial learning and sequence learning success of temporal convolutional networks. We conduct the proposed method on aircraft engine dataset provided by NASA. The experimental results demonstrate that the established graph structure is appropriate and the proposed approach can model spatio-temporal dependency accurately as well as improve the performance of RUL estimation.
      PubDate: 2020-11-17
  • Adaptive fading factor unscented Kalman filter with application to target
    • Abstract: One purpose of target tracking is to estimate the states of targets, and unscented Kalman filter is one of the effective algorithms for estimating in the nonlinear tracking problem. Considering the characteristics of complex maneuverability, it is easy to reduce the tracking accuracy and cause divergence due to the mismatch between the system model and the practical target motion model. Adaptive fading factor is an effective counter to this problem, having been instrumental in solving accuracy and divergence problems. Fading factor can adaptively adjust covariance matrix online to compensate model mismatch error. Moreover, fading factor not only improves the filtering accuracy, but also automatically adjusts the error covariance in response to the different situation. The simulation results show that the adaptive fading factor unscented Kalman filter has more advantages in target tracking and it can be better applied to nonlinear target tracking.
      PubDate: 2020-11-17
  • Attitude dynamic tracking control of an agile satellite using a
           fixed-structured H ∞ synthesis method
    • Abstract: It is a challenging control problem for an agile satellite to observe a rapidly moving target with high dynamic tracking precision. This paper presents a robust and high-accuracy attitude control law for an agile satellite with flexible solar arrays. Model uncertainties caused by vibration of flexible appendages are described as an uncertainty weighting function in the framework of robust H∞ control. However, using the traditional H∞ synthesis method, the resulting dynamic output-feedback controller is not suitable for practical implementation due to its complicated structure and high order. To deal with this issue, an H∞ controller with a fixed proportional-integral-derivative (PID) structure is proposed, and the PID control gains are determined by solving a set of linear matrix inequalities with minimizing the H∞ norm of the feedback control system. Moreover, a feedforward compensator is included to further improve the dynamic performance of the system, achieving a faster response with a smaller dynamic tracking error. Simulations are carried out to demonstrate that the proposed control system can achieve high-precision and rapid maneuver tracking performance for abruptly changing attitude command signals in presence of modeling uncertainties.
      PubDate: 2020-11-11
  • Attitude control strategy of airship based on active disturbance rejection
    • Abstract: The flight performance of the airship is closely related to the attitude control. For the stability of the station-keeping and the rapidity and accuracy of the trajectory tracking, it is necessary to study the attitude control of the airship. This paper proposes a strategy including two parties. First, a novel control mechanism combining moving-mass and tail vector thrust is proposed, and the airship mathematical model is introduced briefly. Second, active disturbance rejection controller (ADRC) is introduced which is developed from classical proportion–integration–differentiation (PID) controller. Considering the special working environment of stratospheric airship, the wind field is added to the simulation as external disturbance. The results show that the system is stable which can track any expected angle of pitch and yaw directions with small overshoot and rise time. In general, with or without the disturbance of 4 m/s wind field, the ADRC performs better than PID controller.
      PubDate: 2020-11-04
  • Adaptive Radau pseudo-spectral optimization for descending trajectory of a
           hypersonic cruise vehicle
    • Abstract: During descending flight of a hypersonic cruise vehicle (HCV), the flight environment is complicated due to the drastically changed atmosphere. It is necessary for the flight trajectory to perform accurate and fast optimization. To solve the nonlinear optimization problem, in this paper, a global adaptive Radau pseudo-spectral method, which is introduced with an hp adaptive strategy (p method to increase the number of points in time interval and h method to refine the interval) is presented. The maximum range and the shortest engagement time are considered, respectively, as performance index to optimize controlling of the attack angle. Using Lagrange interpolation polynomial approximation, the optimal control problem is transformed into a problem of nonlinear programming and solved by a sequence quadratic programming algorithm. Simulation results have shown that the presented method has high computational efficiency and desirable accuracy, with the flying constraints satisfied. It is an effective trajectory optimization method for HCVs.
      PubDate: 2020-11-02
  • An analysis of global ionospheric disturbances and scintillations during
           the strong magnetic storm in September 2017
    • Abstract: Severe space weather events, e.g., solar flares and magnetic storm, can cause significant disturbances to the global ionosphere. The radio frequency signals, such as wireless communications and global satellite navigation system (GNSS) signals, often experience strong scintillations when traveling through the disturbed ionosphere layer. On 6 September 2017, the sun emitted the largest solar flare classified X9.3 since the 24th solar activity week. It triggered the geomagnetic storm and ionospheric storm on September 8, causing severe disturbances and scintillations of ionospheric. In this work, we take this event as the objective to investigate the characteristics of the ionosphere disturbance. First, the temporal and spatial distributions of ionospheric total electron content (TEC) are analyzed using the ground-based IGS data. The change of TEC is highly correlated with that of the geomagnetic indices and the magnetic storm has the greatest impact on low latitudes. Then, a five-point moving average method is adopted to extract the spatial fluctuations based on post-processed electron density and TEC data from COSMIC and GRACE missions. We find they show different disturbance characteristics in spatial distribution. In addition, the GNSS amplitude scintillation index S4 which is available from the COSMIC satellite mission is used to characterize ionospheric scintillation during this event. Weak scintillation occurred in most parts of the world on September 8 2017, while moderate scintillation is mainly concentrated around 120° W and 100° E. Our study can provide a basis for better evaluating the impact of ionosphere disturbance changes on satellite communication and navigation in space weather events.
      PubDate: 2020-11-01
  • Aerial computing—security from missile threats and enhancing PUE
    • Abstract: Data centers have operational challenges due to high cooling costs and the necessity of ensuring physical security to keep data safe. The activities of malicious organizations in countries without sophisticated missile defence systems also necessitate enhancing data center security. The expending of significant power for cooling degrades data center power usage effectiveness (PUE). The use of high altitude platform data centers (HAP-DCs) is proposed to address these challenges. The HAP-DC incorporates a location mechanism which ensures that HAP-DCs have a dynamic location making them difficult targets for aerial missiles. The paper also proposes a stratospheric scheduling mechanism to enhance the HAP-DC’s PUE. The scheduling mechanism ensures that HAP-DCs sited where the stratosphere has best cooling ability are used for workload execution. Analysis shows that the location mechanism enhances safety against missile threats by at least 6.7% and up to 35.4% on average. The scheduling mechanism enhances the PUE by at least 43.8% and up to 81.1% on average.
      PubDate: 2020-10-19
  • Investigation of the effects of angle of attack and tail deflection angle
           on the controlling tail flow field
    • Abstract: In the current study, the flow behavior due to the variation of the tail angle of attack and its deflection has been investigated on a body–tail with a controlling tail. Numerical computations were carried out at a constant velocity of 90 m/s with the tail angle of attack and deflection ranging from 0 to 30 degrees. It provides a deeper understanding of how the aerodynamics of the tail is influenced by the deflection of the tail and the variation of the angle of attack, along with body and nose vortices. The formation of structure and breakdown of vortices along with their effects on the pressure distribution over the tail and the corresponding normal force coefficients derived from the numerical results. As a result, due to increasing the angle of attack or the deflection angle, the high-pressure area extends over the surface of the controlling tail facing the flow. Besides, the effects of angles of attack on the normal force coefficients on the tail are more than deflection angles due to body effects and the corresponding generated vortices. A comparison of numerical results and experimental tests showed satisfying accuracy and provided reliable details on the flow behavior and the highest calculated error rate was 12.8%.
      PubDate: 2020-10-19
  • Characterization and mitigation of multipath fading on multi-frequency
           GNSS signals in urban environment
    • Abstract: The global navigation satellite systems (GNSS) receiver is likely to experience performance degradation in the presence of multipath interferences in indoor and urban canyon environments. There will be multiple reflected signals arriving at the receiver antenna from different paths and directions regarding the different locations of the nearby constructions, causing significant fluctuations and distortions on the amplitude and phase of the direct signals. This is the so-called multipath fading effects and usually exhibit with the random features of temporal, spatial, and frequency diversity across the signal bands. To have a better understanding of the multipath fading effects, a live test was conducted near Lujiazui CBD area in Shanghai. The collected data were processed to characterize the signal attenuations and phase fluctuations on multi-frequency GNSS signals via the detrend code delay, carrier phase, and navigation bit errors. The resulting scintillation index on amplitude, code delay, and carrier phase, e.g., S4, \({\sigma }_{\varphi }\) and \({\sigma }_{\tau }\) can be calculated. Based on these multipath features, the inter-frequency aiding strategy will be utilized for the multipath mitigations in the multi-frequency tracking loop design. The results demonstrate the effectiveness of the multi-frequency tracking algorithm in the urban environment.
      PubDate: 2020-10-19
  • Planning of arrival and departure routes in terminal maneuvering area
           based on high dimensionality reduction environment modeling method
    • Abstract: The efficient design of arrival and departure routes in the terminal maneuvering area plays a key role in increasing airport capacity and reducing traffic congestion. In our study, we establish an arrival and departure route planning model in the terminal maneuvering area, taking into account the airspace environmental constraints and aircraft operational constraints. Then the three-dimensional environment modeling method with a high degree of dimensionality reduction is introduced to improve the efficiency of route planning, and routes are planned sequentially using the A* algorithm in a dimensionally reduced environment. Numerical simulation tests, performed on the terminal maneuvering area of Chengdu Shuangliu Airport in China, show the effectiveness of the proposed method. Each route is given two planning schemes considering the maximum and minimum takeoff or descent slope, and a total of seven routes is generated.
      PubDate: 2020-10-13
  • Visual odometry errors and fault distinction for integrity monitoring
    • Abstract: Visual odometry (VO) has been widely used for many purposes in the past decade. However, the three assumptions of VO are not often met in the reality, and therefore, the uncertainty of VO output (the pose of agent) should be estimated for safety’s sake, which can be done suitably by the integrity monitoring. To construct the integrity monitoring framework of VO, the first step is to establish the model of errors of measurements and calculate the fault rate, which has not been found in the literature to our knowledge. In response, this paper aims at establishing the model of errors of spatial points and calculating the fault rate in the stereo VO based on the feature point method. In this work, we describe the principle of stereo VO based on the feature point method in a deep and comprehensive way. The errors and faults of spatial points in stereo VO are defined, distinguished and classified in detail. The error propagation from pixel to spatial point is deduced, and the model of errors of spatial points is constructed. The KITTI odometry dataset is employed to evaluate the fault rate and standard deviation of errors of spatial points. And multiple sets of sensitive analyses are carried out to address the impact of RANdom SAmple Consensus (RANSAC) threshold, RANSAC iterations and operational scenario on spatial point error and fault rate. This paper could be a reference for constructing the integrity monitoring framework of stereo VO based on the feature point method.
      PubDate: 2020-09-14
  • Space infrared tracking of a hypersonic cruise vehicle using an adaptive
           scaling UKF
    • Abstract: To perform surveillance of a hypersonic cruise vehicle (HCV), space-based infrared system is a reliable and feasible means, which has been putting on the schedule for providing positioning and tracking information of the high-altitude unmanned vehicles. In this paper, a space-based HCV tracking method based on infrared satellite constellation is proposed. The method contains three main parts: constellation coverage analysis, a bearing-only positioning algorithm, and a tracking algorithm. For target tracking, an adaptive scaling unscented Kalman filter (ASUKF) is applied for high estimation performance. Simulation results are presented to show the effectiveness of the method.
      PubDate: 2020-09-05
  • Unscented Kalman filter-based method for spacecraft navigation using
           resident space objects
    • Abstract: The number of resident space objects (RSOs) in orbit has increased dramatically within the last 10 years. While RSOs pose a serious challenge to our continued use of space, these objects also provide an opportunity to improve on-orbit state estimation by detecting and identifying these objects using star trackers. While star trackers are currently used to determine the orientation of their host spacecraft, their utility could be expanded to both position and orientation estimation by harnessing RSO detections. In order for RSO-based optical navigation to be commercially viable, a reliable filter covariance estimate is required. This paper introduces an Unscented Kalman Filter (UKF) for estimating an observing spacecraft’s position and attitude based on RSO observations. To ensure that this filter is reliable, a new assessment technique is introduced where we compare the moving standard deviation and mean of the filter’s estimate error with the predicted error based on the filter’s covariance estimate. We demonstrate the utility of this assessment method by comparing the covariance trusts for our UKF and a previously developed Extended Kalman Filter.
      PubDate: 2020-09-01
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